Why do I draw?

I don't know if you guys have experienced similar encounters but it happens to me quite often - I also have some funny variations on the theme I might turn into a comic.
So outdoor sketching is never an activity I can enjoy in peace - and it's not like I draw in public because I want to show off or draw attention... I kinda hide in a corner all the time.
But maybe I have this happy/intense expression on my face and people want to know why...
At first I did not have an answer to the question. I used to say... I'm addicted to it.
Then I started saying that drawing helps me understand and remember what I see better.
Then again... I think sketches are milestones in life and when I try to explain that I like something to stay there and ground that moment so that the past might lead me to the future... I kind of lose the person's attention already.
hahahaha